>>507509710 (OP)Despite all the grandstanding and propaganda, they don't because they can't.
China's land army is still mostly using 160s soviet hand-me-downs. Every attempt to create a domestically-produced service rifle has failed, so they're just using redesignated AK47s. Their attempt to create a modern MBT failed and they're still stuck with redesignated T-55s. They have next to no amphibious capabilities for their army and their next-generation amphibious combat vehicles are struggling with the same problems that sank all their other domestic weapons development programs.
Their navy sounds impressive in number of ships until you realize the overwhelming majority are coast guard vessels armed with nothing but a short ranged deck gun for maritime strong-arming. Their fleet of Principle Surface Combatants is both smaller and less capable than what the US has forward-deployed in the region and they utterly lack both submarines and anti-submarine warfare capabilities. Missile submarines are the battleship of the modern era and China has exactly 0.
The only aspect of China's military that has modernized adequately is its airforce, but it's still significantly outnumbered in the Pacific by the US and would be fighting over hostile air defense.
Without the capability to quickly breach the strait and overwhelm the Taiwanese army they risk being bogged down in a slow grind that could exhaust their resources, while they're surrounding by large borders with huge land powers that hate them. China's agriculture is not self-sufficient, so if it were to be cut off from global trade it would face famines or worse. The same is true for most of its economy, it relies a lot on importing things it can't secure domestically which puts it in a precarious position if it found itself stuck in a protracted conflict where it couldn't secure its necessary imports.